(a) Field of the Invention:
The present invention relates to a tape reel and, more particularly to an improvement of tape reels, made of synthetic resins, to be assembled in a video tape cassette.
(b) Description of the Prior Art:
FIG. 1 is showing an example of this kind of conventional tape reel. This tape reel comprises a first flange 1 which is flat, a hub 2 formed integrally with the first flange and a second flange so coupled with the hub 2 by an after-mentioned manner as to be parallel to the first flange 1. On the top of the hub 2 are stood a plurality of coupling pawls 4 arranged with equal intervals and the hook portions 4a of the respective coupling pawls are directed radially to the outer side. The base of respective coupling pawls is so formed that the coupling pawls 4 are flexible in some degree to the radial direction and the head is so formed as to have a slant 4b. The openings 5 into which respective coupling pawls 4 will be fitted are formed on the second flange 3 and, when the second flange is forcibly pressed down against the hub 2 after aligning respective openings 5 to respective coupling pawls 4, the engaging edge portions 5a of the openings 5 are snap fitted into the hook portions 4a of the pawls 4 and the hub 2 and second flange 3 will be coupled integrally thereby. That is, at the first stage of the coupling between the openings and pawls, the coupling pawls 4 are bent to the centering direction of the hub through the engagement between the engaging edge portions 5a and slants 4b, but, when the engaging edge portions 5a correspond with the engaging faces 4a' of the hook portions 4a, the pawls 4 will return and the coupling between the hub and second flange will be completed. The space between the engaging faces 4a' of the hook portions and the top face of the hub corresponds to the thickness of the second flange 3.
The tape reel of this type of formation has such an advantage as to be simple in assemblage, but it has such a defect that, when the second flange 3 is pressed upwardly by an external force, the coupling pawls 4 are easily bent to the centering direction of the hub 2 and, consequently, the second flange comes out of the hub and the coupling between the second flange and hub will be imperfect because of the breakage of coupling pawls. Further, in order to mold the coupling pawls 4 having such a shape as mentioned above, it is necessary, as shown in FIG. 2, to use molds 6 and 7 and, consequently, the molded first flange hub is provided with a face S to slide each other when the molded first flange having the hub is taken away from the metallic mold. The existance of this kind of sliding face S results in producing a flash in moldings and also in complicating the formation of metallic mold, and, therefore, results in such a defect as to increase the cost of manufactures. Moreover, as the heads of the coupling pawls 4 protrude over the surface of the second flange when the second flange is coupled with the hub, this is not only disadvantageous for the handling of the tape reel but also so defective as the coupling between the second flange and hub is easily disengaged by the shock caused when the heads touch with other members.